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TCSENDBREAK(3)	       FreeBSD Library Functions Manual		TCSENDBREAK(3)

NAME
     tcsendbreak, tcdrain, tcflush, tcflow -- line control functions

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <termios.h>

     int
     tcdrain(int fd);

     int
     tcflow(int	fd, int	action);

     int
     tcflush(int fd, int action);

     int
     tcsendbreak(int fd, int len);

DESCRIPTION
     The tcdrain() function waits until	all output written to the terminal
     referenced	by fd has been transmitted to the terminal.

     The tcflow() function suspends transmission of data to or the reception
     of	data from the terminal referenced by fd	depending on the value of
     action.  The value	of action must be one of the following:

     TCOOFF  Suspend output.

     TCOON   Restart suspended output.

     TCIOFF  Transmit a	STOP character,	which is intended to cause the termi-
	     nal to stop transmitting data to the system.  (See	the descrip-
	     tion of IXOFF in the `Input Modes'	section	of termios(4)).

     TCION   Transmit a	START character, which is intended to cause the	termi-
	     nal to start transmitting data to the system.  (See the descrip-
	     tion of IXOFF in the `Input Modes'	section	of termios(4)).

     The tcflush() function discards any data written to the terminal refer-
     enced by fd which has not been transmitted	to the terminal, or any	data
     received from the terminal	but not	yet read, depending on the value of
     action.  The value	of action must be one of the following:

     TCIFLUSH	Flush data received but	not read.

     TCOFLUSH	Flush data written but not transmitted.

     TCIOFLUSH	Flush both data	received but not read and data written but not
		transmitted.

     The tcsendbreak() function	transmits a continuous stream of zero-valued
     bits for four-tenths of a second to the terminal referenced by fd.	 The
     len argument is ignored in	this implementation.

RETURN VALUES
     Upon successful completion, all of	these functions	return a value of
     zero.

ERRORS
     If	any error occurs, a value of -1	is returned and	the global variable
     errno is set to indicate the error, as follows:

     [EBADF]		The fd argument	is not a valid file descriptor.

     [EINVAL]		The action argument is not a proper value.

     [ENOTTY]		The file associated with fd is not a terminal.

     [EINTR]		A signal interrupted the tcdrain() function.

     [EWOULDBLOCK]	The configured timeout expired before the tcdrain()
			function could write all buffered output.

SEE ALSO
     tcsetattr(3), termios(4), tty(4), comcontrol(8)

STANDARDS
     The tcsendbreak(),	tcflush() and tcflow() functions are expected to be
     compliant with the	IEEE Std 1003.1-1988 (``POSIX.1'') specification.

     The tcdrain() function is expected	to be compliant	with IEEE Std
     1003.1-1988 (``POSIX.1'') when the	drain wait value is set	to zero	with
     comcontrol(8), or with ioctl(2) TIOCSDRAINWAIT, or	with sysctl(8)
     kern.tty_drainwait.  A non-zero drain wait	value can result in tcdrain()
     returning EWOULDBLOCK without writing all output.	The default value for
     kern.tty_drainwait	is 300 seconds.

FreeBSD	11.1		       January 11, 2017			  FreeBSD 11.1

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS

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